refactor: Replace offset pagination with cursor-based pagination for subscriber listing

- Replace Page and PageSize with Cursor and Limit in ListSubscribersRequest
- Replace Total, Page, and PageSize with NextCursor and HasMore in ListSubscribersResponse
- Add default limit of 20 with max cap of 100 in ListSubscribers
- Replace ListSubscribers call with ListSubscribersCursor in subscriber_crud.go
- Remove unused database import from subscriber_crud.go
- Replace context.Background() with context.Without

apps/api-server/internal/services/subscriber.go

@@ -53,17 +53,16 @@ type UpdateSubscriberRequest struct {
 
 // ListSubscribersRequest is the query-filter payload for listing subscribers.
 type ListSubscribersRequest struct {
-	Page           int                     `json:"page" query:"page"`
-	PageSize       int                     `json:"page_size" query:"page_size"`
+	Cursor         string                  `json:"cursor" query:"cursor"`
+	Limit          int                     `json:"limit" query:"limit"`
 	Status         models.SubscriberStatus `json:"status" query:"status"`
 	OrganizationID string                  `json:"organization_id" query:"organization_id"`
 	Search         string                  `json:"search" query:"search"`
 }
 
-// ListSubscribersResponse is the paginated subscriber list result.
+// ListSubscribersResponse is the cursor-paginated subscriber list result.
 type ListSubscribersResponse struct {
 	Subscribers []models.Subscriber `json:"subscribers"`
-	Total       int64               `json:"total"`
-	Page        int                 `json:"page"`
-	PageSize    int                 `json:"page_size"`
+	NextCursor  string              `json:"next_cursor,omitempty"`
+	HasMore     bool                `json:"has_more"`
 }

apps/api-server/internal/services/subscriber_crud.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 
-	"github.com/nutcas3/telecom-platform/apps/api-server/internal/database"
 	"github.com/nutcas3/telecom-platform/apps/api-server/internal/models"
 	"github.com/sirupsen/logrus"
 )
@@ -44,7 +43,7 @@ func (s *SubscriberService) CreateSubscriber(ctx context.Context, req *CreateSub
 		subscriber.EUICCID = req.EUICCID
 		go func() {
 			// Use derived context for goroutine to respect parent cancellation
-			bgCtx := context.Background()
+			bgCtx := context.WithoutCancel(ctx)
 			if err := s.provisionESIMProfile(bgCtx, subscriber.ID); err != nil {
 				logrus.WithError(err).WithField("subscriber_id", subscriber.ID).Warn("Failed to provision eSIM profile")
 			}
@@ -106,24 +105,25 @@ func (s *SubscriberService) UpdateSubscriber(ctx context.Context, id uint, req *
 	return subscriber, nil
 }
 
-// ListSubscribers lists subscribers with pagination and filtering.
+// ListSubscribers lists subscribers with cursor-based pagination and filtering.
 func (s *SubscriberService) ListSubscribers(ctx context.Context, req *ListSubscribersRequest) (*ListSubscribersResponse, error) {
-	dbReq := &database.ListSubscribersRequest{
-		Page:           req.Page,
-		PageSize:       req.PageSize,
-		Status:         string(req.Status),
-		OrganizationID: req.OrganizationID,
-		Search:         req.Search,
+	// Set default limit if not provided
+	limit := req.Limit
+	if limit <= 0 {
+		limit = 20
 	}
-	subscribers, total, err := s.db.ListSubscribers(ctx, dbReq)
+	if limit > 100 {
+		limit = 100
+	}
+
+	subscribers, nextCursor, hasMore, err := s.db.ListSubscribersCursor(ctx, req.Cursor, limit, string(req.Status), req.OrganizationID, req.Search)
 	if err != nil {
 		return nil, fmt.Errorf("failed to list subscribers: %w", err)
 	}
 
 	return &ListSubscribersResponse{
 		Subscribers: subscribers,
-		Total:       total,
-		Page:        req.Page,
-		PageSize:    req.PageSize,
+		NextCursor:  nextCursor,
+		HasMore:     hasMore,
 	}, nil
 }